Small differencesin the chemistry of tropical trees have big impactson climate change modeling

Adam Robert Martin

Abstract

Tropical forests are some of the most diverse and beautiful places in the world; they also repre­sent some of the last stretches of undisturbed or “frontier” ecosystems on the planet. In addi­tion to playing host to some of Earth’s most amazing and unique plants, animals and insects, tropi­cal forests also play a key role in regulating the planet’s climate. That’s because across the globe, the enormous trees in tropical forests store up to 40-50% of the world’s land-based carbon1. (The oceans also store a massive amount of the world’s carbon, but we’re not taking that into account here). While this is good news for the Earth’s climate, it also means that any human activities that destroy or degrade tropical forests can have an extremely large impact on climate change.

Currently it’s estimated that humans release roughly 9.2 gigatonnes of carbon per year on average2. This amount is so large it is difficult to understand what it means, but this is about equiva­lent to releasing the weight of 9.2 trillion full-grown cows worth of carbon into the atmosphere, mostly as carbon dioxide gas. Much of this carbon is released into the atmosphere when we use fossil fuels in our vehicles, produce agricultural products, or cut down Earth’s forests. Over the past 250 years these activities have led (and will continue to lead) to considerable changes in Earth’s cli­mate including warmer air and ocean temperatures, droughts, melting glaciers and rising sea levels2.

Of humans’ total carbon emissions in recent years from the 1990s through the 2000s, about 12-20% comes from the destruction or degradation of tropical forests – when trees are cut down, the carbon locked up in trees is slowly released into the atmosphere as the wood decays3. This is why measuring and mapping carbon (or performing “carbon accounting”) in tropical forests throughout the world is a critical part of climate change science.